This final project is entitled The Effectiveness of Snakes and Ladders Game as a Medium of Teaching Past Form of Irregular Verbs (An Experimental Research At Eighth Graders of MTs Negeri 1 Jepara in the Academic Year of 2018/2019). The background of the study in this research is based on the phenomena that students in MTs Negeri 1 Jepara usually get bored and unmotivated in learning past form of irregular verbs by using conventional way in the classroom. The students mostly get difficult to remember the form of irregular verbs. One of the ways is using a game. That is Snakes and Ladders Game. The objective of this study is to find out whether there is any significant difference between the students who taught by using Snakes and Ladders Game and students who are taught without using Snake and Ladders Game. This research was held in June 2019 at MTs Negeri 1 Jepara. This study is a true experimental research. The researcher used pre-test and post-test to measure the students’ achievement. The samples of the research consisted of 60 students which were taken by using simple random sampling, VIII A consisted of 29 students as experimental class and VIII B consisted of 31 students as controlled class. In analyzing the data, the researcher used quantitative measurement to find the result. The analysis of the data showed that there was a significant difference of the students’ achievement between experimental and control class. The average of the students’ pre-test is 80,55 in experimental class and 81,09 in control class. After getting treatment using Snake and Ladder Game , the average score of post-test in experimental was higher than control class, 95,03 for experimental class and 90,70 for control class. To measure the significant achievement of the students, the researcher used t-test formula also. The result of post test in experimental and control group showed that the t-value was 2,552 while the t-table of 0,05 as the significance level was 2,000 with 58 the degree of freedom (df). It could be described that the t-value (2,552) > t-table (2,000). Based on the result above, it could be concluded that the Snakes and Ladders Game is effective in improving the students’ past form of irregular verb mastery at the eighth graders of MTs Negeri 1 Jepara. Based on the result of this study, it is expected to be an information material for many teachers especially English teachers in teaching past form of irregular verbs. So, that can produce students who mastery past forms of irregular verbs well.